Truck assemblies for skateboards and rollerskates usually comprise an axle housing secured to the underside of the skateboard platform or rollerskate frame. This housing supports an axle in turn carrying left and right skate wheels usually independently mounted for rotation about the axle.
When a skater passes over uneven terrain or over a curb or the like, objects or edge portions of the curb projecting upwardly between the left and right wheels can engage the axle housing. Such engagement at its maximum can seriously damage the housing and at its minimum simply slow down the skater or decrease his momentum because of the frictional drag.